GM-PFGE在院内肺炎逆行感染途径研究中的应用

Genome Macrorestriction Pulsed Field Gel Electrophosresis in the of Retrograde Route of Transmission for Nosocomial Pneumonia

本文以气管切开 (或插管 )病人为研究对象 ,用防污染标本刷 (PSB)采集标本 ,用质粒DNA图谱、酶切图谱、全基因组DNA稀有位点酶切脉冲电场电泳 (GM PFGE)等基因分型方法 ,前瞻性观察NP的发生情况。结果 11名患者有逆行感染存在 (发生率为 10 2 % ,占感染病例的 2 2 % ) ,即在胃液分离出病原菌一、二天后 ,PSB在咽部及下呼吸道也检出相同的细菌 ,应用上述分子生物学技术进行同源性分析 ,聚类分析相似系数为 10 0 %。将美兰经胃管注入病人胃内 ,而后在咽部及下呼吸道也有蓝色分泌物检出。

The study was conducted in patients in department of neurology and neural surgery of three teaching hopitals requiring mechanical ventilation or tracheostomy, the secretion of lower respiratory tract was collected by protected specimen brush(PSB)and the specimens were carried out for quantitative culture of bacteria.At the same time,the bacterial samples of gastric aspirates were collected to culture and the pH value of gastric aspirates was determined using a digital acid-base analyzer.All patients were monitored for development of nosocomial pneumonia every 2 days.The gene typings of the bacterial from lower respiratory tract secretion and gastric aspirates were take by plasmial profile analysis,restriction andonuclease fingerprint analysis and genome macrorestriction-pulsed field gel electrophoresis(GM-PFGE)in the same phenotype bacteria In 11(22%) case of nosocomial pneumonia,the identical organisms were isolated first in the gastric samples and then one to two days later in tracheal secretion.They were very homolgous,exhibiting the same fingerpriting in plasmid profile,endonuclease fingerpint and GM-PFGE.Two days after being perfused into the stomach through masogastric tubes,Methylent blue was found in the secretion of throat and lower respiratory tract.The bacterial counts in gastric aspirates increased significantly with gastric pH.Conclusion The retrograde route of transmission is confirmed to be existed and it is one of the risk factors in nosocomial pneumonia.The occurrence of nosocomial pneumonia is significantly associated with rising of gastric pH.